With heightened security requirements at facilities across the country and overseas, an increased need has developed for devices that can easily operate as gates or gated barriers and meet necessary crash barrier requirements. Such devices may be entirely stand-alone systems or the devices may act as an upgrade or improvement to previously existing gates or gated barriers.
A prior art device in use at Argonne National Laboratory since the mid-1980s provides an approach that has been improved with the present invention. The prior art device is simply a straight steel pipe with a wire rope cable through it. The cable ends are connected so that the cable forms a loop, part inside and part outside the pipe. The pipe is attached to the fence and the cable loop hangs below the pipe. A variation of the prior art device appears to include metal standoffs welded to the pipe and clamped to the cable to hold the cable above the pipe. The pipe is attached to the gate, and two bollards with hooks will catch the cable loop when impacted in such a way that the pipe passes through the bollards.
One weakness of both the prior art devices is that they permit the full force of impact to bear as a concentrated load on a single point in the cable. Additionally, these systems do not provide protection against the potential cutting action of the pipe ends or the standoffs on the wire rope when either device experiences dynamic stresses such as those that result from the impact of an automobile against such a device.
The preferred embodiment of the present invention offers advantages including, but not limited to, the following: 1) providing for distribution of the loading, 2) transferring critical impact loading, 3) eliminating sharp edges that could cut a cable, 4) using an improved catch horn design, and 5) including a modified reinforcement technique for a bollard to facilitate installation. Once installed, the preferred embodiment of the present invention does not require operation of any active elements to perform its catching function.